Molded article



c. A. BA'JER MOLDED ARTICLE Filed April 1939 UflH i BY I M ATT I K7 IPatented May 15, 1945 I i UNITED MOLDED ARTICLE Charles A. Bauer,Newburg, Ind., assignor to Hoosier Cardinal Corporation, Evansville,Ind., a corporation of Indiana \Application April 3, 1939, Serial No.265,746

V 1 Claim. (Cl. 41-22) My invention relates to articles formed oftransparent materialand has for its primary object the creation of anillusion whereby the,article will bear adesign which appears to beformed of a different material embedded within it. Such articles may beused for purely decorative purposes, for name plates, for push-buttonssuch as the push-buttons for automobile horns, for contaihers orcontainer-covers, or for countless other purposes. I In carrying out myinvention, I make the article of transparent material. with the designrecessed into its ,rear face, and then I render the recess walls opaque,as by applying thereto an opaque coating material. Preferably, theunrecessed portions of the rear face of the article are also renderedopaque, again as by application of an opaque coating material which maybe of a materials of contrasting colors. When such an article is thenviewed from the front, the design will have the appearance of beingformed of a material different from that Of the body of the a articleand as embedded from the rear in the material of which the article isformed. In some cases, the design appears as if out out of solidmaterial, secured to a suitable base, and covered with a dished cover ofthin transparent material.

Several methods may be employed for applying contrasting colors to therecess walls and to the rear face of the article. For example, suitablecolored coating material may be applied, as by spraying, simultaneouslyto the recess walls and to the rear face of the article, and then wipedor otherwise removed from the rear face of the articolor contrastingwith that employed on the recess walls. Desirably the article is formed.of transparent plastic material, the design being created by the mold inwhich the article is molded.

The accompanying drawing illustrates my invention: Fig. 1 is a plan viewshowing a simple lens-likearticle embodying my invention; Fig. 2 is anisometric view, in partial section, of the article shown in Fig. 1; Fig.3 is an isometric view of the rear face of the article shown in Fig.1;Fig. 4 is an isometric view of a mask which may be used in coloring theback of the article illustrated in Figs. 1 to" 3; Fig. 5 is an enlargedsection in a plane normal to the rear face of an article embodying myinvention; Figs. 6, '7, and 8 are sectional views illustrating. suitablemountings for articles, such as name plates, embodying myinvention; andFig. 9 is an isometric view of a box the cover of which embodies myinvention.

The article illustrated in Figs. 1 to 3 inclusive consists of a simplelens-shaped body H! such as might be used to display a name, a monogram,or any other desired design. The article is'shown as circular and aspossessing a plane rear face and a cle to leave coating material, asindicated at 12 in Fig. 8, only on the recess-walls. After the coatingmaterial on the recess-walls has dried, a secondcoating material I3 ofcontrasting color may be sprayed onthe .rear face of the article.Because the coating materials used are opaque, the second coat will notbe'visible through the first coat on the recess walls; and as a result,when the article is viewed from in front, the recess walls and the rearface will possess contrasting colors. If this method of applying thecontrasting colors is employed, it is of advantage to have the rear faceof the article plane in order to facilitate removal therefrom of thecoating material first applied.

In another method of applying coating materials of contrasting color, Iemploy a mask which protects either the recess walls or the unrecessedportions of the rear face of the article when the first coat is appliedand which may then be removed when the second coat i applied. If thismethod is used I prefer to employ a mask which convex front face;biit'it is to be understood that this particular shape, as well as theparticular design shown, are to be taken as merely illustrative.

The design, whatever its shape, is formed by recessing the rear face ofthe, body III, as indicated at H, such recesses being formed eitherduring the operation of molding the article or by cutting after thearticle is molded. After the design is formed, the recess-walls, anddesirably also the rear face of the article, are rendered.

opaque, as by the application thereto of opaque coating material.Preferably, the recess-walls and rear face of the article are coatedwith opaque protects the recess walls and to apply first a coatingmaterial of the color which is to appear as background when the articleis viewed from in front. Such a mask may take the form of a casting,such as is indicated at I4 in Fig. 3, which fits into the 'recess orrecesses forming the design.

I flnd that the illusion of solidity of the coated recess walls isenhanced if those walls extend approximately normally-say within 10",and

preferably within 5, of a right-angleto the 1 rear face of the article,as is clear from Fig. 5.

The illusion is also more striking if the depth of each recess is madegreater than its width. The

recess walls, for the creation of the "best 'efiect,

should meet the rear face of the article in a fairly well defined edge,as indicated at IS in Fig. 8. This well defined edge I! not only aids inthe tween creation of the illusion but also facilitates the maintenanceof a sharp line of demarcation becoating materials of contrastingcolors.

I am aware that it has heretofore been proposed to form glass articleswith designs created by recesses in their rear faces, and also old torender the recess-surfaces opaque by paint or otherwise. It is apractical impossibility, however, to mold glass with the well definededges indicated at [5 in Fig. 5 and also a practical impossibility tomold a glass article with a recess having a depth greater than its widthand having side walls which are approximately parallel to each other andnormal glass. Clear synthetic plastics are free from the objectionswhich, as just noted, are possessed by glam; and in forming articles inaccordance with my invention, I therefore prefer to use such" materials.The plastic used should be clear, so that the coated recess-walls areclearly visible through it. Desirably, the material is is not essential.styrene, as well as acrylic resins and cellulose aceto-butyrate, areexamples of plastics which I have found to be satisfactory.

Since the interfaces between the body of the colorless, although thatCellulose acetate and polyto the rear face of the article and thecolored coatings applied to the rear face thereof and to the recesswalls are visible through the article, it is essential for the besteffects that each be uniform in appearance throughout its extent. I havefound that best results in this respect are obtained if the coatinmaterial contains a solvent for the plastic of which the article isformed. For example, a suitable coating material which I havesuccessfully employed'with articles made of cellulose acetate consistsof about 25% flake cellulose acetate, 10% color pigment, and 65% methylacetone. This compomtion may also containa small proportion (say about2%) of any of the common plasticizers for cellulose acetate. As anotherexample,

I have used successfully on articles made of polystyrene a coatingmaterial consisting of about 10% nitro-cellulose, 10% alcohol-solubleester gums-10% color pigment, 35%,- butyl acetate, and 35% iso-propylalcohol.

When coatingv materials such as those described are used, the solvent inthe coating material tends to penetrate and soften the surfaces to.which the coating material is applied, with the result that a permanentand uniform bond between the body of the article and the coatingmaterial is obtained. For best results, the solvent used should be onewhose volatility is so co-, ordinated with its rate of attack on theplastic that the desired bonding effect is obtained before the solventpenetrates too deeply into the body of the article; for if the solventpenetrates too deeply the appearance of the coated surfaces, when viewedthrough the article, will be adversely affected, and if the attack ofthe solvent on the plastic'is insuillcientan inadequate bond isobtained. The volatility of the methyl acetone used in the compositionmentioned above as a coating material for application to articles madeof cellulose acetate may, in some cases, be so great that the solventwill evaporate before the desired bond is obtained; in which event smallproportions of di-acetonealcohol may be added to the coating material.The attack on the plastic of the other coating material disclosed abovemay be controlled by varying the relative proportions of the butylacetate and iso-propyl alcohol, an increase in the P p rtion of butylacetate increasing the rate of attack, and vice versa. The mostdesirable solvent-composition is that which will most quickly produce apermanent and uniform bond. Because of the transparent nature of anarticle embodying my invention, certain restrictions are placed upon themanner in which it is attached to any support or base upon which it isto appear, as many otherwise suitable attaching means would be visiblethrough the transparent body of the article. In Figs. 6, '7, and 8 Ihave illustrated three different arrangements by which an articleembodying my invention can be mounted without interfering with itsappearance. In the arrangement illustrated in Fig. 5, the lens-shapedarticle it shown is mounted in a shallow sheet-metal cup 20 ofcorresponding shape, the peripheral edge of the cup 20 being turned overthe circumferential .edge of'the article l0 asindicated at 2|. The cup20 may have secured to it, asby welding or soldering, a mounting screw22 by means of which the article may be mounted upon any desired base orsupport.

In the arrangement illustrated inv Fig. 6, the rear face of the article23 shown is recessed over an area somewhat greater than that occupied bythe design formed by the groove II to leave a peripheral flange 24. Aplate 25., desirably of metal, to which a mounting screw 26 is secured,

flange then distorted over the periphery of the plate 25. This form ofmounting is especially convenient when the article 23 is ofthermoplastic material, as the desired distortion of the.

inner. edge of the flange 24 may be secured through the use of anannular heated member 21 having an external diameter slightly less thanthat of the article 23. When such a member is forced against the rearface of the article, the material is softened and forced radiallyinwardly over the edge of the plate 25, as indicated at 28. If thisoperation unduly disturbs the appearance at the periphery of the opaquecoating material asviewed through the article, additional coatingmaterial may be applied. I

Where the design of the article permits, I may employ the mounting meansillustrated in Fig. 7.

In that arrangement, after the recess-walls have screw-threaded hole 3|adapted for the reception of the screw by which the article embodying myinvention may be secured to the desired support. Conveniently, the plug30 m of the same material as the article and, -before being insertedinto the recess, is coated with a suitable solvent which will soften theouter surface of the plug and the coat ing material and firmly bond themtogether. The opaque coatingv material with which the recess walls arecovered before the plug 30 is inserted prevents the plugitself oranymounting screw in the hole 3| from being visible through the article.

Instead of being embodied in an article intended for. attachment to asuitable base or support, my inventiommay also be embodied in articleswhich need no mounting. Thus, I have illustrated in Fig. 9 a box 35having a cover 36 which bears a design formed, in accordance with myinvention, by grooves in the inner face of the box-cover, the walls ofsuch grooves, and preferably also the ungrooved portions of the innersurface or the cover, being covered with opaque coating material.

My invention has a wide field of application. It has been used in themanufacture of small decorative panels of various kinds, name plates,automobile horn-buttons, coasters, control knobs, and in small boxessuch as cosmetic compacts; and many other uses will be obvious. Wherethe article is. backed, as by the use of the cup 20 of Fig. 5 or theplate 25 of Fig. 6, the background color may be applied to the backing;but I prefer, where a colored background is employed, to apply itdirectly to the article in the manner indicated above.

I claim as my invention:

An article of the class described, comprising a body of transparentplastic having recesses in its rear face, the walls of said recessesbeing provided with a coating of opaque material, and a member adaptedfor co-operation with articlemounting means, said member being receivedin one of said recesses with the opaque coating intervening between itand the walls of the associated recesses whereby the member will not bevisible from the front of the article.

CHARLES A. BAUER.

